A carbon dioxide-rich gas contains at least 60 mol % of carbon dioxide, or even at least 80 mol % of carbon dioxide.
The remainder of the gas may contain one or more of the following components: oxygen, nitrogen, argon, nitrogen oxide (NO or NO2 or N2O), carbon monoxide, hydrogen, mercury.
Purification may be carried out in one or more successive steps of partial condensation and/or by distillation.
In numerous cryogenic applications, the production of cold by the unit is performed by vaporizing a liquid at a pressure that is low enough to reach sufficiently low temperatures. Because the liquid is not necessarily obtained in the method at this pressure, it is necessary to expand it, and this may generate the production of gas. The gas thus obtained will not generate a great deal of cold because it will transfer only sensible heat. It is therefore advantageous to limit the production of gas by supercooling the liquid before expansion.
The patent application filed under number FR-1256778 offers a solution for the layout of the cold box of a CO2 capture unit with the exchange line separated into two parts, one of them technologically simpler making it possible to reduce the risk of the cold box freezing solid.
The patent application filed under number FR-1256771 offers a solution for incorporating cryogenic membranes into the cold box of a CO2 capture unit.